Aerodynamic surface for dirigible bombs



Feb. 5, 1952 R. D. WYCKOFF 2,534,826

AERODYNAMIC SURFACE FOR DIRIGIBLE BOMBS Filed May 31, 1946 3 Sheets-Sheet l .,77';tc' Q a2 '27 "2 RJKJ- PH D. \NYGKOFF Feb. 5, 1952 R. D. WYCKOFF AERODYNAMIC SURFACE FOR DIRIGIBLE BOMBS Filed May 31, 1946 5 Sheets-Sheet 2 ALPH D.WYC3KOFF Feb. 5, 1952 R. D. WYCKOFF 2,584,326

AERODYNAMIC SURFACE FOR DIRIGIBLE BOMBS v Filed May 51, 1946 3 Sheets-Sheet 5 Qwuwwbo'b RALPH D. WYCMOFF Patented Feb. 5, 1952 Ralph-wD. .Wyckofli; Pittsburgh fm, assignor to. Gulf Research: & Development Company, Pitts: burgh, Pa.,.- xa i corporation of {Delaware Application Mayer; ,194e,::serial No. 673i373 5;Claims.-. (01-10%3.)

This invention: relates :to" aerodynamic surf aces for "a dirigible or" directionallycontrolled-=bomb-- the bomb is executing controlling: or "steering maneuvers.

In th'e-operation of bomb's whiclraren'ot merely released but subsequently -:maneuvered or steered v to their target, one-must 1 provide essentiall-y *two dimensional control? Thus, in' general} one must provide range control and azimuth controh steerm in these-two directionsbeing accomplished by the use of appropriately connected'rudders'or" elevators. These -ruddersor elevators may be controlled in a variety of ways; usually either remotely through theme of radio; orautomati cally by the use of self-contained target-seeking apparatus. It'isobviouslynecessary to maintain the above-mentioned two directional axes on the bomb at a definite orientation withrespect to similar axes onthe surfaceofthe ground in order to properly isolate thefunctions of rudders and elevators for steering in azimuth" or range; respectively. Rudders-may-be used-to steer the bomb to theleft'or rightin'azimuthb'y means of their operating mechanismsand similarly elevators may be used to control the bomb upward or downward fl in" range through similar I or auxiliary apparatus. The rudder and elevator operating mechanisms perse do not-form the;

subject matter of this :invention and' are thereforenotdescribed in detail. Examples of such" mechanisms may be found in 'copending' applica'-' tion by Wyckoff, -Mo1nar, -Palmer and Bl'ewett, now' U. S. Patent 2,466,528; and also incopending applicationzby Wyckoif, Fitzw-illiamand Salvetti; now U.'S. Patent 2,495304;

Deviation of r the :path of it-helbomb isaccomplished by? the: applicationytheretoi -of so-called aerodynamic lift surfacess. These surfaces serve the function of setting-yupaerodynamic:forces approximately normal .to.: the: lineof: flight :of

the b'ombsoas sto :defl'ect its pathaiini the jdesireddirection; The attitude :ofithese surfaces imth'e wind'streamiwhich is experienced by the falling bomb is controllediby the Laction ofrthe aforementioned rudders and; elevators. The: termlift is hereqused in: the: general: aerodynamic sense and is'not restricted. :to: vertical or: gravitas tional lift The 1 lift. surfaces. produces-the :required: forces to deviate the -path.wof;.-theibomb.:in.;theifollowing; manner; When :the 51121311218101 at. symmetricakzairfoil, is parallel, .to- .the .wind;stream, no lift is. :produced, but -whenthe airfoil cordpresentsianl-tangle to.-.the :direction-..of the windstreamf (an angle: of attack). then-lift forces'areagenerated which are: at -,right-. angleswto the-. wind=stream:* Alter=- I natively, I by the"; usewof r relatively small .iflapsi'at the trailing ,edgenof-rannairfoil :sur'face; thevefiec tive angle-of attack ofthe airfoilumay' be .controlled: A "stabilizing tail-wsurfaceeis usually: ap-w plied to arbombin order'towproduce: thei-weather-w cock stability;.@efiect u necessary: to keep :the: *axis 7 of the bomb headed-r into theawwindvstreams-and" keepwthe bomb lfroma-tumblingxin :fiight."z" By "the use-. of-acontrol -flapson. the: trailing? edge -:of the stabilizing- -.tai--l surfaces,- aerodynamicsforces 'may 5. be set up whi'ch'producera yawingmomenti': This 2 yawing-.-moment applied at -the rearward'rportion of. the rbomb serves eta-maintain ther'entire bomb: axis :at astable angle-10f: attack with :respect rto the wind: stream, so.- th'at the rlift surfacesa fixedi tothe-bomb may provide" the-desired aerodynamic; lift component manifested as a side thrust which? Willa-deflect the fipath-vofithe. bombxint the desired direction.--. I l

Lift"surfacesrforbombs-have-heretoforerusually'i been in the form of a flat-fin cruciform structures at :the -tail-.-of: the i bombs: It has been' :foundin wind tunnel :as well as-inactual ?drop testsethat :-if "i a bomb with the usual fiat-fin cruciiormestruce turevis giyeniy an attitudeeof': both-yaw and" pitch with respect to the:airrstream-forrthe-zpurposeofe producing a desired ideviatiorr ill-':th8'1i1l60fffiiht, therevresults ea stendency: forrthe bombz toerotatee on its axis, this rotation being due to" thezasym.- metric aspectxof theistr-ucture:close=.to the bomb body *when' viewed =fromvthe. direction'sof fiight: I01.-

, wind stream. An elementary explanationcoi' jthis efiectmay; be found; in thewfa'ct that-:a: flat-fin cruciform structure presents a lvarying projected-1 area-to: the wind -:stream:if it, i is rotated-about :a-i: yawed longitudinal axis, and the bomb itendsrtoiz roll-into awppsitiomwhichuprojects the greatest area to the awindwstreamz; In: additionait 'wilzlftbee foundxithatra cruciformnfinstructurer'inherently involvesi'strongr roll: asymmetry due .to::the?shad= ingaeffectaof the: surfaces ."lntionetplane 'on th'ose Fin".

the other: planeiiwhen-ztzthez cruciform-type strucew ture--.: is' subjected to: combinedcliyawz and .pitch angles; of'rattack. rotation-.z'must berpreevented"? or controlled? in: orderi toczmaintain the rudders andt'elevatorssinztheir respective 'or'ienta- Inrorder tor-maintain the fioper'atiomof rudd'rs andzelevators "in their respective: directions; it is obviously anecessarysto eliminate oravoid '"rota; tion of tithe .b0mbi-':ab0utiit's' longitiidirlal axis;

. since any such rotation would result in confusionch magnitude as to exceed the stabilizing cacity of the ailerons. 1

This invention is based on the discovery that control surface having cylindrical symmetry ay be used as a lift surface on such a bomb, 1d will produce little or no rotation even though ven an attitude of considerable yaw and pitch 'sher singly or both together. In its simplest rm, this invention comprises the use of a lift rface for a dirigible bomb, said lift surface tving cylindrical symmetry with respect to the :is of the bomb and having a cylindrical form as near cylindrical in form as practical limitams permit. The advantages of such a cylin- "lcal control surface in elemihating roll torque we not heretofore been appreciated. It is accordingly an object of this invention to 'ovide a control surface for a controllable bomb which the control surface is so shaped and -iented as to produce inappreciable roll torque 1' the bomb during its flight.

Another object of the invention is to provide a steerable bomb a control surface disposed .ld spaced in such manner as to have circular lindrical symmetry about the bomb axis.

Another object of this invention is to provide control surface for a bomb steerable in two )mponents and in which inequality of the steerig efiect of any one of a plurality of control surtees for deflecting the bomb will not produce ppreciable roll torque on the bomb in flight.

Another object of this invention is to provide 1 a remotely controlled bomb a control surface aving cylindrical symmetry about the axis of the omb. These and other objects will be apparent from be following specification of which the drawings re a part and in which Fig. 1 is a diagram of a bomb having the usual ruciform flat-fin tail structure; 1

Fig. 2 shows the bomb of Fig. l in a deflected vttitude and illustrates its asymmetrical aspect o the wind;

Fig. 3 shows a control surface having circula ylindrical symmetry as contemplated by my inentlon;

Fig. 4 shows a diagram of a lift surface having ircular cylindrical symmetry used together with steering surface also having circular cylindrical y metry;

Fig. 5 shows another disposition of control :urfaces having cylindrical symmetry;

Figs. 6 and 7 show a form of the invention in which the control surface has circular cylindrical mmetry and in which the steering surfaces are nounted on the radial supports thereof;

Figs. 8 and 9 show a form of the invention in which the control surface has octagonal cylinirical symmetry and in which rudders, elevators, md ailerons are disposed in an alternative preferred manner;

Figs. 10 and 11 show a form of the invention ,n which a lift surface having circular symmetry is used together with a rudder, elevator, and aileron assembly having octagonal cylindrical symmetry; 1

Figs. 12 and 13 show a form of the invention in which both lift and steering surfaces have octagonal cylindrical symmetry.

Referring to Fig. 1, numeral I0 represents the body of a bomb and having cruciform tail fins ll, usually four in number, and each having aerodynamic flaps connected through mechanical linkages to'a steering mechanism housed in body ill or in the tail structure connected thereto. One pair of these flaps, such as l2, may be used to control the azimuth, while another pair, such as l3, may be used to control the range. Alternatively, in a simple form of such a device one pair of flaps, for instance I2, may be used as ailerons and the other two for steering purposes,

such an arrangement resulting in control in one direction only. A remotely controlled bomb of this type is described in the aforementioned copending patent application of Wyckoff, Molnar,

' Palmer and Blewett, now U. S. Patent 2,466,528.

The purpose of the ailerons is to maintain the axial roll orientation of the bomb. They may be controlled by means of a gyro, and operate so as to counter any tendency of the bomb to roll out of its proper orientation. In a bomb controlled in two directions the aileron action may be superimposed on the motion of either the rudders or elevators by means of appropriate interconnection of control linkages. The bomb may be equipped with contact fuze l4 and arming device i5. Devices l4 and [5 will be omitted on subsequent drawings of the invention since they form no part thereof per se.

In Fig. 2 the body of the bomb I0 is shown in the position of approximately 15 of both yaw and pitch. In this case, the line of flight as indicated by the arrow Hi from the center of gravity I1 is not in the direction of the axis of the bomb nor is it'in the plane of any of the control surfaces. The control surfaces H ex perience a wind or air stream from the side such as indicated by arrow IS. The particular angular attitude such as here illustrated is the natural result of attempts to steer the bomb by means of rudders l2 and elevators l3, both rudder and elevator being applied simultaneously or in rapid succession. One may readily observe from this picture that while three of the control surfaces I l are in the air stream H3, in general at least one control surface, such as ll,

may be partially shadowed, so to speak, by the body of the bomb and therefore experiences much less aerodynamic force than the other surfaces II. The result of this asymmetry is a torque tending to set up rotation of the bomb about its longitudinal axis l9, and such rotation ultimately results in complete confusion between rudder and elevator control. To eliminate such rotation of a bomb having a cruciform tail structure has been found to require prohibitively large and powerful ailerons.

Again referring to Fig. 1, while rudders i2 0perate together so as to produce deflection of the bomb in the same direction, any inequality in their rudder eifect results in the production of rotational torques about the longitudinal axis of thebomb. The same is true of inequalities in the elevators. Such inequalities in steering effect may result from partial shading of the lee steering surface when the bomb is in an attitude of yaw or pitch as shown in Figure 2, as Well as from mechanical inequalities.

This invention is based on the discovery that by the use of a cylindrical stabilizing surface such as shown in Fig. 3 the tendency foraxial rotation of the bomb is substantially eliminated; Here the body of the bomb Ibis-equipped with a tail structure having radial" supports 26 holding a cylindrical surface 2|; The bomb and its stabilizer surface 2i have cylindrical symmetryabout the longitudinal axis 22. When such a-cylindrically" symmetrical surface 2| is given any combined yaw and pitch attitude, the area projected onto the wind stream direction is substantially invarient' with roll orientation. Hence norotational tendency arises from variation in projectedarea. Likewiseany-liftforces developed by the cylindrical surface 2|, due-to an imposed angle of" attack; can only be exhibited as radial'forces' with no tangential components and no rotational tendency arises even if"st'rong shading effects are present. Supports and lift surface 21" maybestreamlined according to. good aerodynamic practice.

Fig. 6 illustrates a manner in which bomb of Fig. 3 may be steered to control its direction. The bomb body I8 equipped with the auxiliary cylindrical..liftsurface 2|. held by radial. supports ZGhas, in addition, a cylindrical steering surface 23 supported on radial structure 24 mountedorr gimbal orsocket 255. An arm 25 connected to the steering surface support structure 24 is actuated by the control mechanism 2? housed inside thebomb Mechanism 21 is di rected by signals which areeither remotely produced by the bombardier or originate. in a target-seeking mechanism. The cylindrical steering surface 23 here acts to give the bomb the necessary yaw or pitch attitude to its line of flight such thatthe lift surface 2| produces the necessary and desired path deflecting force. Properxroll orientation is-provided by means of ailerons 66 and 6!. mounted: on operating rods.

which are actuated inopposite directionsby a gyro control mechanism 62 inside the bomb.

Fig. 5 shows another relative disposition of an auxiliary cylindrical lift surface 28 supported by radial structure 29 from the body of the bomb, whereas the smaller steering surface 23 may be supported and operated from the tail as steering direction, and the attitude of steering surface 23 may be controlled by arm 26 actuated through mechanism 21 as in Fig. 4.

In the. construction of a steering surface mounting device such as indicated by 25 in Figs. 4 and 5, it is necessary to take into consideration hinge forces required to produce the necessary deflection of surface 23. These hinge forces may become considerable at high velocities, and it has been found desirable to separate rudder and elevator control into separately controllable functions instead of combining them on one surface, such as surface 23 of Figures 4 and 5.

Fig. 6 is a side view and Fig. 7 a tail end View of a bomb having circular lift surface supported by radial struts 36, each of which has a tab 31 used for purposes of control. One may, for instance, use eight radial supports 36, two of these supports 36 being equipped with rudders 38, two being equipped with elevators 39, and the other four having ailerons 40. While such a structure d lacks perfect circular cylindrical symmetry; the lack: of symmetry is relatively small and results inonly small rotational forces easily handledby small ailerons The embodiment of Figs. 6 and 7 eliminates the roll tendency set up by shading of the lift surfaces, this being a large part of the-rotational effect encountered in previously used-bombs with flat-fin tailstructure. However,- rotational tendencies due toshadin of the steering surfaces 38 and 39 maystill be present and produce serious roll instability. These roll tendencies may be further eliminated by the use of the preferred disposition of steering surfaces shown in Figs. 8 and 9.

Fig. 8 shows the side view and Fig. 9 a tail end view of a preferred'form of control surface in which a cylindrical lift surface '41 carries the rudders 42 and elevators 43. In order that steering elements 42 and-43 mayhave straight-hinges for convenience in manufacturing, the lift surface 4! has the form of an octagonal cylinder thus permitting the insertion of steering tabs 42 and 43 in its straight portions. Rudders 42 and elevators'43 are connected by means of rods 44- and 45, respectively, to control mechanisms inside the bomb tail itself. Ailerons 46 may beplaced on the radial supports 4'! and operate to maintain. the bomb in proper orientation. Details of the mechanism of a remotely controlled bomb of this type is described in aforementioned copending patent application of Wyckoif, Fitzwilliam and Salvetti, now U. S. Patent 2,495,304; Such acontrolsurface as 4|, while not. having. complete circular symmetry, has been found to be so nearly thereto that only small ailerons 36 are required to maintain orientation even though considerable yaw and pitch are set up by the steering elements 42 and. 43. Furthermore, inequalities in thesteering effects of elements 42 and 43 give rise'to radial forces and not rotational forces, thereby eliminating any roll tendency from this cause.

Fig. 10 shows a side view and Fig. 11 a tail end view of a bomb having a circularly symmetrical auxiliary lift surface 48 connected to the body of the bomb through radial supports 49 and having a stabilizer and control surface 50 of octagonal shape and equipped with steering elements 5| and 52 similar to those of Fig. 9, ailerons 53 being provided to control the axial roll orientation as in Figs. 8 and 9. The use of a cylindrical lift surface such as 48 placed forward on the body of the bomb approximately at its center of gravity greatly increases the aerodynamic lift available and hence the maneuverability of the bomb is increased. Surface 48 may be increased in thickness to have the shape of a streamlined airfoil as shown in Fig. 10.

Figs. 12 and 13 show a bomb in which two control surfaces have been applied to the tail assembly in order to reduce the overall diameter, particularly at the bomb body. While in this case auxiliary lift surface 54 is not as effective as the surface 48 of Fig. 10, placed near the center of gravity of the bomb, there are other compensating advantages of reduced space. Rudders 55 and elevators 56 serve to steer this embodiment in a manner similar to that described in connection with Figs. 8, 9, l0 and 11, while ailerons 51 on radial support struts 58 serve to maintain orientation also as explained in preceding figures. Lift surface 54 may have the form of a circular shroud cular symmetry may be tolerated and the result' small rotational forces may be overcome by 1 use of moderately sized and moderately powd ailerons. Radial struts 58 and 59 represent ue fiat-fin cruciform effect but this effect may minimized by keeping their size as small as ssible and by angularly staggering struts 58 and about the axis of the bomb. vly invention is not to be limited to the emliments shown in the drawings as these are for rposes of example only. Any cylindrically iped control and lift surfaces may be used, such iped surfaces bein effective in reducing roll 'ques which tend to throw the bomb out of con- 1. While the cylindrical surfaces shown are the form of a cylindrical shell, the shell thick- ;s may be increased and streamlined, as is gen- Llly done in such structures. What I claim is: L. An aerodynamic surface for a dirigible bomb nprising a surface having the form of a pristtic shell and having operable aerodynamic ps mounted on and parallel to a straight porn of the trailing edge of said shell.

2. An aerodynamic surface for a dirigible bomb nprising a fixed surface having the form of :ylindrical shell affixed to the bomb and a secd fixed surface having the form of a prisitic shell afiixed to the bomb and having an op ible aerodynamic flap mounted on and paralto a straight portion of the trailing edge of 1 whose thickness varies in the axial direction thereof in the manner of an airfoil and a second fixed surface affixed to the bomb and having the form of a prismatic surface'whose thickness varies in the axial direction thereof in the manner of an airfoil and having an operable aerodynamic fiap mounted on and parallel to a straight portion of said second surface.

5. An aerodynamic surface for a dirigible bomb comprising a surface having the form of an axially symmetrical prismatic shell, said shell varying in thickness along its length in the manner of an airfoil, radial supports fixing said surface to the bomb so that its prismatic axis of symmetry coincides with the axis of the bomb, aerodynamic flaps operably mounted on and parallel to a straight portion of the shell and aerodynamic ailerons operably mounted on said radial supports.

RALPH D. WYCKOFF.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 1,388,932 Centervall Aug. 30, 1921 2,137,385 Butler Nov. 22, 1938 2,359,515 Fanger Oct. 3, 1944 2,393,604 Berger Jan. 29, 1946 2,406,293 Hammond Aug. 30, 1946 2,419,866 Wilson Apr. 29, 1947 2,425,558 Ohlendorf Aug. 12, 1947 FOREIGN PATENTS Number Country Date 512,985 France Oct. 27, 1920 820,266 France July 26, 1937 

